Would Yom haShoah be associated with other tragedies, connected to heroism--or stand on its own?

There was a strong tradition that all great tragedies were to be incorporated into the sacred round of Judaism.
The great question was: What day should be used?

From the beginning, one of the deep issues in dealing with the Holocaust has been the issue of continuity or discontinuity. Given the totality of the tragedy, was this event something unique or just another in the long list of tribulations, expulsions, disasters that mark Jewish history?

Classically, tradition tried to choose a day connected to the event, preferably an anniversary date such as Passover, Hanukkah, or Tisha B'Av. But what could be the anniversary of the Holocaust? This was no one-time affair; it went on year-round for years. Perhaps a period of the year should be set aside, but when?

A General "Day of Kaddish"

So massive was the scale of the Holocaust killing and so reckless its speed that for most of the dead there was no firm knowledge of the Yahrzeit, the actual date of death. Indeed, for many of the dead there were no survivors of the immediate family to say Kaddish. Finally, in 1948, after some earlier incidents and rulings crystallized the question, the Israeli rabbinate proposed a Yom Kaddish Klali, a general Day of Kaddish to be said for all those for whom there were relatives to say the prayer but no known date of death, and for those for whom there was no relative to say Kaddish but others would say it for them.

Given the high number of victims in the above two categories, the rabbinate also proposed that this general (or communal) Kaddish day be the day of Holocaust commemoration. The day chosen was Asarah B'Tevet, the tenth day of the tenth month of the Hebrew calendar. This is a fast day that traditionally marks the beginning of the siege of Jerusalem which led to the destruction of the Temple.

Why the Tenth of Tevet?

The choice of the tenth of Tevet is worth consideration. Clearly, its selection reflects the idea of incorporating the newest tragedy into the chain of tradition without introducing any halakhic innovation. This decision affirmed that the destruction of the Temple remains the paradigm and acme of Jewish tragedy. But why not incorporate this event into the ninth of Av, as most of the medieval tragedies had been?

The answer is instructive. Of the four days of mourning for the Temple, Tisha B' Av was the strongest in terms of participation by the Jewish people. Shivah Asar B'Tammuz was far less observed. The third fast day, Tzom Gedaliah, was more neglected yet. Of all the fast days however, the tenth of Tevet was by far the weakest.